oa Case study: Successful application of 3D depth processing in Eromanga Basin, Queensland

The majority of seismic imaging performed on Australian land seismic data is carried out using time migration processing sequences. The Eromanga Basin in Queensland, Australia has geological features which are difficult to resolve using time migration.

Here we demonstrate the use of pre-stack depth migration to successfully image such features. The pre-stack depth migration used successive iterations of residual curvature analysis to update the velocity model using a top-down approach. Major geological horizons and well data were fed into the 3D tomographic model updates to arrive at a final velocity model that images the subsurface and is consistent with the well-ties.

The final pre-stack depth migrated image resulted in a significantly improved interpretation when compared to the pre-stack time migrated equivalent. Observed unconformities and complex structures are resolved within the depth image.

We demonstrate that depth processing has resulted in a more confident structural understanding of the survey area. We believe that due to general proximity of reservoirs to formations containing velocity anomalies, that depth investigation be warranted to more accurately image potential exploration targets.